The invention is directed to a method for setting up virtual connections in switching equipment operating according to an asynchronous transfer mode.
Methods of this type are already known from the periodical INTERNATIONAL JOURNAL OF DIGITAL AND ANALOG CABLED SYSTEMS, Vol. 1, an article by K. A. Lutz on pages 237-243 (1988) and from the Conference Paper from the International Switching Symposium, 15 through Mar. 20, 1987, Proceedings, Phoenix, USA, Bouch, K. Bruninghaus, and B. Schaffer 3(1987), pages 602-608, both incorporated herein by reference. Virtual connections are set up for packet switching with methods of the known type. For this purpose, routes sought via links as well as via ATM (Asynchronous Transfer Mode)--switching matrix networks, are selected and defined. Routes via ATM switching elements and via ATM links are defined within an ATM switching matrix network.
It is important when seeking, selecting, and defining routes (route search) for virtual connections to be newly set up that routes already occupied by virtual connections can be made use of for other virtual connections, insofar as free transmission capacity is still available on these routes. For this purpose, it is known--for example for every link in a multi-stage ATM switching matrix network--to store the transmission capacity that is respectively free at the moment, i.e. is available for setting up new virtual connections, in an ATM link occupation memory. This transmission capacity that is still free, i.e. is still respectively available for setting up new virtual connections, can, for example, be equal to the difference between the overall transmission capacity of a link and the transmission capacity already made use of by the virtual connections set up thereover. The latter, for example, can be the sum of all peak bit rates of the corresponding virtual connections.
It is already known for seeking, selecting, and defining routes for virtual connections to be newly set up that the respective transmission capacity that is still free, i.e. is still available for setting up new virtual connections, is compared in terms of size to the transmission capacity required for the new virtual connection to be set up, which, for example, may correspond to the peak bit rate of this virtual connection.
The invention is directed to simplifying the procedure of route searching to be very frequently sequenced in methods of the type initially discussed. When a size comparison of the type addressed above is then carried out for every route search, then particularly strict demands for the corresponding processing equipment result therefrom, namely because the operations of setting up new virtual connections, on the one hand, are many per time unit, i.e. occur relatively frequently and, on the other hand, dare not last too long. Waiting time problems when setting up connections are disturbing and undesirable.